jy-mcu bluetooth and rambo, stuttering

[yoon]

Hi, I've connected a JY-MCU version 1.05 to pins 1-4 of my RAMBo board (on a Lulzbot AO-101). I am able to connect at 115200 baud, and have regular communication with pronterface (monitoring and setting temperature, homing, jogging, etc). But when I print anything with arcs, the movement stutters quite noticeably.

The hot end ends up melting the deposited filament into a blob, and anything curvy takes forever to print. Straight segments aren't affected. Is this latency inherent in bluetooth, or could I be using other pins or settings to correct it?